What follows is a drawing of my fifth skimmer. All of these skimmers have been built out of standard sizes of PVC. If you are thinking about building a skimmer you might want to think twice. Unless you do it right the first time the cost of DIY can quickly add up to the cost of a high quality manufactured skimmer. This is, as I said, my fifth attempt. Skimmers 1 and 2 were just piles of trash. Skimmers 3 and 4 were not that bad if you like an air pump driven skimmer. In fact I have Skimmer 3 running on my green water experiment and parts of Skimmer 1 are in Skimmer 5.
One saving grace this skimmer has over a manufactured skimmer is cost. For $30-$60 U.S. you can have a 4"x2' or 4"x6' skimmer. You can vary the length of any of the PVC sections that you will soon see. The major downfall is the cost of a quality pump and a venturi. If you are planning on a great skimmer you better plan on a pump and venturi anyway. Those air pumps are OK, and I lived with a couple for a long time, but if you really want a lot of air in your skimmer you better plan on a pump and venturi.
You know I have to do this. The standard disclaimer. I can not be responsible for what happens if you build this skimmer. I, for one, have not been able to fit 5 gallons of water into a 2.5 gallon jug. It is not a pretty picture. The carpet is very good at absorbing water and it is a great test for insulation of electric wires. And heck, a couple weeks later I think the carpet was dry. Remember don't look for me to pay for anything. I am just a poor hacker/aquarist trying to make this a better place for all my fellow info-aquarist. Another thing I did this as a mindless act of beauty and a senseless act of kindness that you, as a interested person, could dig it. Maybe you could better my world. Dig in and make something happen. I may not be able to move a mountain but I can give the knowledge contained in this document to anyone willing to look for it.
And now for a description of parts and modifications.
This is just a 5" section of PVC the is cut on an angle of about 35 degrees and a small notch cut in the straight side. What I do is silicone a 4.5" x 6" piece of Plexiglas on the angled side. This allows for viewing into the collection cup and an angled top for the collection cup. The notch is cut in the other side the hole (H1) is not blocked. The angle decides the length of this section. I will just warn you once and I will do it here. I really don't measure every section. I just cut where I think it should be.
This is where the waste exits the skimmer. You should be able to figure out what to do with this, but what I do is attach a 6' length of 5/8" ID vinyl hose and dump it into a 2.5 gallon jug.
This adapter is glued to item (4) below and a single 5/8" hole (H1) is drilled through the side at about midway. After item (4) is glued into place where to put the hole should be obvious. Make sure the hole is drilled so as to be sure not to hit item (4).
This section is just glued into items (4) and (6). If could find a male 2" trap adapter I would not use this section. But for now this is the way I have done it. Make the section as short as you can as its length will reduce the area of viewing into item (7) below while the skimmer is running.
This adapter is glued to item (5) above. This adapter can slide on item (7) to adjust the skimmer.
You can vary the length of this tube when you learn a little more about your skimmer. The pump and venturi you chose will decide the optimum length of this tube. I have purchased this tube from a local plastic supply house. The name of this tube is Extruded Round Clear Acrylic Tubing. It costs about $2.50 per foot and is very easy to work with. Start with a section about 10 inches long. That should be about right. Well that is what I started with and I made my version of this skimmer about 4.5' tall. You might also be able to find a clear tube called CLEAR BUTYRATE TUBING the correct size. I have found this stuff at Ain Plastics. I am sure they are in that new 800 WWW site.
This adapter is glued to item (9) below. This adapter can slide on item (7) to adjust the skimmer.
I make this about 2" long to allow item (7) to slide around. This allows the length of the riser tube to vary about 2".
This section of PVC should be about 12" long so that the water flowing into hole (H2) below is not at the surface of the water. I like it this way so the surface of the water is not being disturbed by the water flow. The length of this section can the varied to change the length of the skimmer. Maybe some day I'll invest in some clear PVC but it works fine without it.
This adapter has a hole (H2) drilled in the middle of the lower half. I use the 4" PVC connectors on this skimmer to make the walls thicker. I could have just drilled holes into a section of 4" PVC but 4" PVC is only 1/4" thick. I liked the idea of having 1/2" of stock to work with rather then 1/4". Hey if you don't like it build it your way.
This section of PVC gets drilled through with holes (H2) above and (H3) below. The length of this section and be varied to change the length of the skimmer. I made this length about 2.5' and then I split this in half. I use a plastic collar to join these two sections together. This make this skimmer able to be opened for cleaning and building. I have taken some pictures of this skimmer so you can see what I am talking about. Look and the end of this page and maybe I will get the film developed.
This adapter has a holes (H3) and (H4) drilled into it.
Hole (H3) is drilled in the middle of the upper half. This is where I will place the return from the recirculation pump to a venturi and return the water here.
Hole (H4) is drilled 90 degrees from hole (H3) and in the middle of the lower half. I will glue item (34) into this hole. This is where I will feed the recirculation pump.
This section of PVC gets drilled through with holes (H2) above and (H3) below. The length of this section and be varied to change the length of the skimmer.
This flange gets drilled with hole (H5). All I can say about location of this hole is BE CAREFUL. The main reason I work with 1" PVC is that it fits between the top and bottom of this piece of stock PVC. I did drill through the bottom of a couple of these in my time. It gets a little expensive at $3.50 each and the loss of 3" of 4" PVC. Measure very carefully. Take your time. If all else fails I have found that after everything is in place about 1/2 pint of PVC glue dump in here and left in the sun for a week to dry seems to seal any little imperfection.
This PVC is cut down the center about 3" and then another cut removes half the stock. Doing this creates a barrier for the siphon break. In the past I have built air driven skimmers and have found that I like this area as wide open as possible. And you never know when you might drop an air stone or brick, on accident, down here. This also acts to block some air from going out the siphon break.
I wrap this with Teflon tape and then thread into item (17) above.
The length is up to you. Using this here make the entire siphon break flexible. Just insert items (19) and (21) and maybe install a couple hose clamps.
This connector is threaded into item (22) below and inserted into item (20) above.
The length is up to you but plan on 12"-24".
Using this union here allows the upper section of the siphon break to be adjustable about 3".
Plan on starting with about 6". Use at least 4" as you will want to adjust the height of the siphon break here.
You will want this section pretty long. Mine is about the same height of the top of item (7), maybe even taller.
This gives a nice constant water level in the skimmer.
You might want to be sure this empties into a sump or something. I connect another 1" slip to thread and 1" thread to barb and a little more 1" vinyl hose and ...
These adapters are cut to remove some of the stock that won't come in contact with the walls of the PVC.
Remove most of the stock from the smaller side of this elbow. It makes for a nice smooth directional port.
These item are glued together and then into holes (H2) and (H3).
This is where I will connect the feed of the recirculation pump.
This section of PVC is glued into hole (H4) and to the two item (33) and (35). I insert this PVC about 2.5" so the the elbow (35) is pointing directly down the center of the skimmer.
Point this down and glue inside skimmer to items (34) and (36).
This PVC gets glued to item (35) and should be a couple of inches above the bottom of the skimmer.
Holes (H2) thru (H5) couldn't be drilled with a standard sized hole saw so I purchased a tool called a DIAL SAW. This device costs about $15 and is very handy. It will make any size hole in the range of 1 1/8" to 2 1/2". Take your time and drill a couple of test holes in some other material to make sure the size is what you want. The fit should be snug but allow a section of 1" PVC to pass through.
So that is about it. Except for a couple things.